Wavelet packets multicarrier CDMA in correlated fading channel

The channels of mobile communication always suffer serious frequency-selective fading. Multicarrier as one of the important modulation technique, has been proposed to cope with it for its advantage in frequency diversity. Traditional multicarrier is characterized by the fact that the time-domain orthogonality is based on the function of sine and cosinesquareOwing to the fixed frequencies, multicarriers may not perform satisfactorily under frequency-selective fading. This paper adopts a new class of carriers, wavelet-packet orthogonal carriers. The combination of the wavelet waveforms in different nodes in a wavelet-packet full binary tree enables frequency diversity capability and facilitates implementing multi-rate streaming, which retains well time-domain orthogonality as well as to provide subband diversity to mitigate frequency-selective fading. A new result on the probability density function of the sum of square is proposed. So a closed-form expression of the bit error rate of this multicarrier CDMA system is derived, where the correlated Rayleigh fading channel with an additive white Gaussian noise is employed. The simulation results reveal that correlation among channels decreases the performance of the system. Wavelet-packet multicarrier modulation performs well under same fading situation than general MC-CDMA.